PROJECT SUMMARY ADHD is defined by behavioral symptoms that are not well defined in relation to underlying neurobiology or mechanisms. Using mechanisms to define its nosology and predict outcomes is expected to be more powerful than the current approach, but this hope has only partially been realized. Surprisingly, the parameters influencing willingness to maintain cognitively effortful activities have not been examined systematically. That is, existing data indicate ADHD is associated with differences in reward valuation and processing, which are influenced by delays to reward delivery. However, it is unknown whether ADHD is associated with higher levels of aversion of exerting cognitive [mental] effort, and altered reward x effort interactions. Accordingly, this application aims to address this knowledge gap by examining individuals' preferences between rewards associated with minimal effort and alternatives with higher payoff but higher effort costs (?effort discounting?). Thus, the overall goal of this proposal is to characterize the differences in biases and tradeoffs during effort- related decision-making in ADHD, using an effort discounting methodology, and to identify factors associated with these differences. To accomplish our overall goal, the proposed research will take advantage of a well- defined sample of ADHD-diagnosed and healthy control individuals initially recruited in 2007 (the ?parent study?) to address three aims: (1) To examine the subjective perception of effort in youth diagnosed with ADHD and healthy controls using tasks in which they are required to exert varying levels of cognitive effort (sustaining attention, engaging working memory processes), (2) To determine whether ADHD is associated with steeper discounting of larger, more effortful rewards than matched controls in tasks where effort requirements have been matched in subjective effort ratings, and (3) To explore relationships amongst indices of effort discounting, and theoretically-related traits (e.g., grit, distress tolerance), biomarkers of effort-related decision- making (eye movements and pupil size), and cognitive measures assessed in the parent study. Successful completion of the aims would permit us to better characterize ADHD-healthy control differences, and lay a foundation for more computational approaches to ADHD diagnostic criteria.